KMT2D maintains neoplastic cell proliferation and global histone H3 lysine 4 monomethylation

Abstract

// Changcun Guo 1,2 , Lee H. Chen 1,2 , Yafen Huang 1,2 , Chun-Chi Chang 1,2 , Ping Wang 1,2 , Christopher J. Pirozzi 1,2 , Xiaoxia Qin 4 , Xuhui Bao 1,2 , Paula K. Greer 1,2 , Roger E. McLendon 1,2 , Hai Yan 1,2 , Stephen T. Keir 1,3 , Darell D. Bigner 1,2 , Yiping He 1,2 1 The Preston Robert Tisch Brain Tumor Center at Duke and Pediatric Brain Tumor Foundation Institute, Duke University, Durham, NC 2 Department of Pathology, Duke University, Durham, NC 3 Department of Surgery, Duke University, Durham, NC 4 Institute for Genome Sciences and Policy, Duke University, Durham, NC Correspondence: Yiping He, email: // Keywords : MLL2, isogenic cell line, gene knockout, enhancer Received : October 30, 2013 Accepted : November 1, 2013 Published : November 3, 2013 Abstract KMT2D (lysine (K)-specific methyltransferase 2D), formerly named MLL2 (myeloid/lymphoid or mixed-lineage leukemia 2, also known as ALR/MLL4), is a histone methyltransferase that plays an important role in regulating gene transcription. In particular, it targets histone H3 lysine 4 (H3K4), whose methylations serve as a gene activation mark. Recently, KMT2D has emerged as one of the most frequently mutated genes in a variety of cancers and in other human diseases, including lymphoma, medulloblastoma, gastric cancer, and Kabuki syndrome. Mutations in KMT2D identified thus far point to its loss-of-function in pathogenesis and suggest its role as a tumor suppressor in various tissues. To determine the effect of a KMT2D deficiency on neoplastic cells, we used homologous recombination- and nuclease-mediated gene editing approaches to generate a panel of isogenic colorectal and medulloblastoma cancer cell lines that differ with respect to their endogenous KMT2D status. We found that a KMT2D deficiency resulted in attenuated cancer cell proliferation and defective cell migration. Analysis of histone H3 modifications revealed that KMT2D was essential for maintaining the level of global H3K4 monomethylation and that its enzymatic SET domain was directly responsible for this function. Furthermore, we found that a majority of KMT2D binding sites are located in regions of potential enhancer elements. Together, these findings revealed the role of KMT2D in regulating enhancer elements in human cells and shed light on the tumorigenic role of its deficiency. Our study supports that KMT2D has distinct roles in neoplastic cells, as opposed to normal cells, and that inhibiting KMT2D may be a viable strategy for cancer therapeutics.